Roller bit



June 3, 1941' c. M. HANNUM. 2,244,617

ROLLER BIT Filed Jan. 14, 1959 ENTOR.

CHARLES M. NNUM ATTORNEYS Patented June 3, 1941- The National Tool Company, Cleveland, Ohio, '5

corporation of Ohio I Application January 14,1939, Serial No. 250,955 3 Claims. (01. 255-11) The present invention relatesto a roller bit particularly adapted for use in the well drilling art.

It is the general object and nature of the invention to provide such a roller bit having improved qualities of cutting action, efliciency and durability. Such improvements have primarily to do with the roller r rotary cutters which rotate on a substantially horizontal axis and are traversed around the longitudinal axis of the hit. As such a rotary cutter rolls over the surface to be cut, its teeth deliver an impact against such surface, and where a plural number of cutters are employed, one cutter necessarily follows in the path of the other. The removed material from the cutting action must be kept cleaned from the cutters, free of the surface to be cut, and removed from the bottom of the drilled hole as promptly and efliciently as possible. The present invention therefore deals essentially with the problem of providing a roller bit cutter tooth capable of withstanding the impact action without losing its cutting efliciency, the prevention of "tracking of the cutter teeth, viz., pro'per distribution of the contact points of the teeth of the several cutters over the surface to be cut; and finally, the prompt and efficient cleaning of the cut material from between the cutting teeth and its removal from the zone of cutting action.

To the accomplishment of the foregoing and related ends, said invention, then, consists of the means hereinafter fully described and particularly pointed out in the claims.

The annexed drawing and the following description set forth in detail certain mechanism embodying the invention, such disclosed means constituting, however, but one of various mechanical forms in which the principle of the in-,

vention may be used.

In said annexed drawing:

Fig. 1 is an elevational view partially in section of a roller bit embodying the principle of my invention; Fig. 2 is a more or less diagrammatic view illustrating the cutter tooth cleaning action; Fig. 3 is an enlarged cross-sectional view of one of the cutter teeth; and Fig. 4 is an enlarged cross-sectional view of one of the cutter teeth after a period of usage.

Now referring more particularly to the drawing, there is shown therein a roller bit head indi-' cated generally at I, with a tapered thread portion 2 for attaching the head to a bit shank. Downwardly extending arms 3 and 4 are carried by the head I and support each end of the cutter shaft 5. The intermediate portion of the cutter shaft [is supported by a bridge 6 extending downwardly from the central portion of the head I. A pair of rotary cutters land 8 are Joumalled upon the shaft 5, such as by the combined roller and ball bearings 9 and I0.

Each of the cutters I and 8 is in the shape of the frustrum of a cone with the base outermost. The exterior surface of the cutters I and 8 is occupied by annular rows of pyramid shaped teeth I l, the rows being axially spaced from each other. Helical .gashes I! extend across these rows of teeth. The hand of the helixes of the gashes i2 is to the left, in each of the cutters 'l and 8. Since the cutters I and 8 will have a direction of rotation about the shaft 5 which is mutually opposite, the direction 0f the helical gashes [2 will therefore extend away from the direction of rotation of the respective cutters. Thus, assuming that the cutter "i rotates in a direction shown by the arrow A, and the cutter 8 in a direction indicated by the arrow B, the

direction of the helical gashes i2, from the inside to the outside of the cutters, therefore, is inclined away from or extends opposite to that of their respective directions of rotation.

Such disposition of the helical gashes i2 therefore facilitates the rapid and efllci'ent cleaning .of material from between the teeth H and its removal directly to the outer side of the cutter and to the periphery of the hole being cut.

- Nozzles l3 are mounted in the head I and adapted to direct a stream of washing fluid, i. e., water, against the cutters I and 8. It will be noted, by reference to Fig. 2, that the nozzle I3 is so positioned as to deliver its stream of water to the back side of the cutter 8, or in a direction opposite to the direction of rotation 18 of the cutter.

The arrow C in Fig. 2 indicates the direction of bodily travel of the cutter 3. The cutter teeth to the left of the vertical axial plane V are entering or about to enter the surface to be out. The cut material, therefore, tends to pass to the right of the vertical plane V and some of it of course lodges between the teethof the cutter and is carried upwardly toward the spray i3. The lateral range of the spray i3 is substantially as indicated by the dotted lines a and b in Fig. 1. The small ing action since they place the gashes I2 in lateral communication with each other. Thus, not

only is the cut material efllciently dislodged and removed from the cutter teeth, but such cleaning action is also effected in such a manner that none of the cut material is in any way carried on over into the path of travel or zone of new cutting action of the cutter.

The axis of the tool head I is denoted by the center line C. L. The row of teeth II on the innermost side of the right hand cutter I is spaced a distance d radially from the center line C. L., so that they make a track which falls substantially in the groove [4 between the teeth ll of the left hand cutter 8. This is further illustrated by reference to Fig. 1 where the distance d has been transposed from the right hand to the left hand side of the center line C. L. Succeeding rows of teeth toward the outside end of the cutter I are correspondingly spaced with respect to the center line C. L. and thus their respective tracks correspondingly fall intermediate the tracks of the rows of teeth on the left hand cutter 8. Uniform distribution of the contact points of the teeth II in both cutters is thus obtained, and the disadvantage incident to tracking is thus eliminated.

As will best be seen by reference to Fig. 3, inserts I5 of a relatively hard durable material, such as tungsten carbide or haystellite are mounted in the tops of the teeth H. Ti: tops l6 of the inserts are substantially coincident with or project a slight amount above the tops I! of the teeth ll. These inserts It: can conveniently be assembled in the teeth by first cutting radial recesses or slots into the tops of the teeth, then inserting slugs of the harder metal, in the form of the inserts, into the slots and permanently fixing them therein by a heat treatment bonding. Alternatively, the inserts l5 can be installed in the slots by flowing the harder metal in a molten condition therein, much in the manner of a welding process.

The improved cutting action of the teeth, by reason of the presence of the inserts I 5 is illustrated in Fig. 4 which shows a tooth after a, period of considerable usage. The relatively softer metal, such as steel, forming the body of the tooth H, has worn away in the regions indicated at I8 due to impact and abrasion. The harder metal of the insert l5 being less subject to the action of impact and wear, remains substantially intact and operates as a leading edge and contact point for the tooth II. By reason of such construction, it will therefore be seen that the teeth of the cutter are in a sense self-sharpening, as distinguished from the teeth of the cutters previously used wherein the homogeneous material forming the body of the tooth is worn fiat and frequently mushroomed across its top so that its cutting or impact action is progressively impaired. Since the cutting or impact action is a function of the pressure per unit area explained, change being made as regards the,

mechanism herein disclosed, provided the means stated by any of the following claims or the equivalent of such stated means be employed.

I therefore particularly point out and distinctly claim as my invention:

1. A roller bit comprising a head, means for rotatably supporting a rotary cutter in said head, said cutter having a series of axially spaced annular rows of teeth and helical gashes extending across said rows of teeth, said gashes being inclined from the inner side to the outer side of said cutter in a direction away from thedirection of rotation thereof, and a nozzle mounted in said head in such position as to direct a stream of water against the surface of said cutter in a direction opposite to the direction of rotation thereof.

2. A roller bit comprising a, head, means for rotatably supporting a rotary cutter in said head on a substantially horizontal axis, said cutter having a series of axially spaced annular rows of teeth and helical gashes extending across said rows of teeth, "said gashes being inclined from the inner side to the outer side of said cutter in a direction away from the direction of rotation thereof, and a nozzle mounted in saidhead in such position as to direct a stream of water to that side of a vertical axial plane of said cutter opposite to its direction of its travel.

3. A roller bit rotary cutter in the shape of a frustrum of a cone having a series of axially spaced annular rows of teeth and helical gashes extending across said rows of teeth, said gashes being inclined from the inner side to the outer side of said cutter in a direction away from the direction of rotation thereof.

CHARLES M. HANNUM. 

